Electroencephalographic Indicators in Default Mode, Habituation, and Visual-motor Association in Female College Students.

BACKGROUND: Oscillations, action, and postsynaptic potentials in glial-neuronal ensembles integrate the spectral power (SP) of electroencephalographic (EEG). Our objective is to propose SP indicators of healthy brains (control groups) based on the default mode and their modifications by habituation and visual-motor association (VM-asso), to support diagnostic and rehabilitation processes. However, important differences seem to exist between men and women. Therefore, we aim to analyze EEG characteristics in a female sample. SUBJECTS AND METHODS: In the current study, EEG was recorded at rest with closed eyes before and during repeated photostimulations (RPh) and before (pre) and during association of RPh with switch pressing (VM-asso) in 70 female adults. EEG was analyzed using UAM/INR software, which removes artifacts, identifies corresponding signals, selects 20 samples (2-s) from each condition, applies Welch's periodogram to calculate and average the absolute power (AP; AAPs) of áµ¹, θ, α, and ß, before and during learning, and emits data to a spreadsheet. Differences in each condition were evaluated using non-parametric tests. RESULTS: The AAPs were different; in habituation, áµ¹ and θ increased significantly in fronto-frontal (FF) and frontocentral and decreased in the other leads. During association, they increased in FF and decreased in the other three regions. α AAP decreased in all leads except in FF during habituation, and the decrement was lower in the association. ß AAP increased in all leads during both learning conditions. CONCLUSION: The SP and the topographic distribution are descriptive parameters of habituation and VM-asso; we propose them as EEG indicators.

Correlación del funcionamiento ejecutivo y la potencia absoluta del EEG en niños / Correlation of excutive functioning and the absolute power of the EEG in children

RESUMEN: Introducción: La potencia espectral en reposo a menudo se considera como un marcador robusto de la función cerebral; sin embargo, pocos estudios la han asociado con una función específica. Objetivo: Analizar la relación entre la potencia absoluta (PA) del EEG con el desempeño en las tareas de funcionamiento ejecutivo en niños. Método: Investigación transversal correlacional en 30 niños (8.6 ± 1 años). Se realizó el EEG con ojos cerrados y análisis de derivaciones bipolares. Con la transformada de Fourier se calculó la PA en el espectro de 1.6-30 Hz. Se aplicó la batería NEUROPSI Atención y Memoria y se calculó el Indice de Atención y Funciones Ejecutivas (IAFE). En función de éste, se comparó la PA con Kruskal-Wallis y valor Z, coeficiente de Spearman para la correlación con las subpruebas. Resultados: Los niños con alteraciones severas ( x - = 63 ± 8 IC 95% [57.2, 68.5]) tuvieron mayor PA delta en F1F7, P301 y P402, así como valores Z cercanos a 2 DE en F7T3, F3C3 y F8T4 en frecuencias lentas. Las correlaciones fueron significativas (rho, p ≤ .05) entre el IAFE con la PA delta en P301 (-.57), P402 (-.43) y T5O1 (-.37); con PA alfa principalmente en zonas fronto-temporo-parieto-occipitales izquierdas. La puntuación en Detección Visual y Fluidez Semántica se relacionó con la PA alfa. Discusión y conclusión: El rendimiento en actividades de FE es diferente en relación con la PA delta frontal y parietal. Existe una relación inversa entre la PA delta y alfa en reposo con la atención y fluidez (245/250).

ABSTRACT: Introduction: The resting EEG power is considered as a robust marker of brain function; however, a few studies have associated it to a specific function. Objective: To analyze the relationship between EEG absolute power (AP) with performance on tasks of executive functioning in children. Method: Correlational cross-sectional study of 30 children (8.6 ± 1 year). EEG was performed with eyes closed and bipolar leads. With the Fourier transform AP was calculated in the spectrum of 1.6, 30 Hz. NEUROPSI Attention and Memory was applied and the Index of Attention and Executive functions (IAFE) was calculated. Based on this, the AP was compared with Kruskal-Wallis and the Z value, Spearman coefficient for correlation with the subtests. Results: Children with severe impairment ( x - = 63 ± 8 CI 95% [57.2, 68.5]) had higher delta AP (α ≤ .05) in F1F7, P301 and P402, and Z values near 2 SD in F7T3, F3C3 and F8T4 at slow frequencies. Correlations were significant between the IAFE and delta AP P301 (-.57), P402 (-.43) and T5O1 (-.37); with AP alpha mainly on left fronto- temporo - parietal- occipital areas. The score in Visual Detection and Semantic Fluency inversely related to AP alpha frequency. Discussion and conclusion: Performance on tasks of executive functioning is different in relation to the frontal and parietal AP delta. There is an inverse relationship between AP delta and alpha at rest with attention and verbal fluency.

Evolución de la potencia absoluta, relativa e índices de ritmos electroencefalográficos en estudiantes de primaria, licenciatura y maestría / Evolution of absolute and relative power and indices of electroencephalographic rhythms in elementary, college, and graduate students

Resumen: ANTECEDENTES: La función cerebral resulta de la actividad eléctrica en redes glío-neuronales, integradas de forma activa por interacciones sensoriales, motoras y reguladores. Redes que oscilan desde la infancia y se modulan por diversos factores de maduración, incluyendo procesos educativos. OBJETIVO: Identificar el espectro de potencia separado en delta (δ), theta (θ), alfa 1 (α1), alfa 2 (α2), beta 1 (β1) y beta 2 (β2) y su topografía en los hemisferios cerebrales de niños, jóvenes y adultos para establecer indicadores EEGc. MÉTODO: Se estudiaron tres grupos de 16 participantes: niños en primaria (GN), estudiantes de licenciatura (GL) y de maestría (GM). Los padres y los participantes otorgaron su consentimiento. En el aparato Nicolet se registró el EEG utilizando el sistema 10/20. Se analizaron muestras bipolares, con T Fourier se obtuvo la potencia absoluta (PA), se calculó su promedio (PPA), la potencia relativa (PR) y los índices de frecuencias lentas/rápidas. Las diferencias se evaluaron con Kruskal Wallis y la comparación de Dunnet para sub-grupos. RESULTADOS: El PPA de seis frecuencias fue mayor en GN que en GL y GM. En éstos fue similar con excepciones, relacionadas con la distribución topográfica. El índice δ/α fue mayor en GN con particular distribución topográfica y θ/α fue más variable. La PR de α fue mayor en GL y GM comparados con GN, la de θ y de δ en algunas derivaciones, fueron mayores en el GN. DISCUSIÓN Y CONCLUSIÓN: En la maduración cerebral disminuye la PA debido a la integración de más ensambles glío-neuronales, que presentan mayor asimetría en determinada frecuencia. Estos perfiles establecen indicadores para compararlos con futuros registros EEG.

Abstract: ANTECEDENTS: Cerebral function results from the electrical activity in glial-neuronal networks, integrated proactively through sensory, motor, and regulating interactions. These networks oscillate since early life and are modulated by diverse maturation factors, including educational processes. OBJECTIVE: To identify the power spectrum separated in delta (δ), theta (θ), alfa 1 (α1), alfa 2 (α2), beta 1 (β1) y beta 2 (β2), and their topography in cerebral hemispheres of children, youngsters, and adults to establish qEEG indicators. METHOD: We studied three groups of 16 participants each: elementary school children (CG), undergraduate students (UG), and graduate students (GG). Parents and participants granted their consent. The EEG was recorded (Nicolet) following the 10/20 system. Bipolar samples were analyzed. Absolute power (AP) was obtained with Fourier transform; its average (AAP) relative power (RP), and slow/fast frequencies and indices were calculated. Differences were assessed with Kruskal Wallis and Dunnet's comparison for subgroups. RESULTS: The AAP of six frequencies was higher in CG than in UG and GG. Frequencies were similar with exceptions correlating with topographic distribution. The δ/α index was higher in CG with a particular topographic distribution, θ/α varied more. RP of α was higher in UG and GG than in CG; that of θ and δ were higher in some leads of CG. DISCUSSION AND CONCLUSION: During cerebral maturation, AP diminishes due to integration of more glial-neuronal ensembles, presenting greater asymmetry in a giving frequency. These profiles establish indicators for comparison with future EEG recordings.

Desynchronization/synchronization of parasagittal EEG rhythms during habituation to photostimulation in adults.

INTRODUCTION: Learning by habituation implies a gradual diminution of the organism's responses to non-relevant stimuli. These responses, resulting from electrical oscillations of the brain, can be analyzed through quantitative electroencephalography (qEEG). OBJECTIVE: To characterize the absolute power (AP) in the range of delta (δ), theta (θ), alpha (α), beta (ß) in cortical parasagittal regions during habituation to photostimulation (RPh). MATERIAL AND METHODS: We studied 81 undergraduate students. The EEG was recorded in a Nicolet; awake subjects with closed eyes were photostimulated (5 Hz for 2 s, 20 times, RPh). The UAMI/Yáñez program identifies the RPh signal, chooses and collects 2-sec samples before (Pre) and during RPh, and instruments the Welch periodogram, which integrates the absolute power (AP) of δ, θ, α, and ß. We calculated the average AP (AAP) in Pre and RPh per frequency and lead. AAP differences were assessed with non-parametric tests. Linear regression was used to plot the AAPs of each Pre and each RPh sample, representing the resulting slope with its statistical significance. RESULTS: RPh increased the AAP of δ in frontal and frontocentral leads of both hemispheres, and its slopes were ascendant. AAP of θ increased in fronto-frontal and diminished in the other three leads, its slopes were ascendant in right central parietal and parieto-occipital leads. AAP of α increased in fronto-frontal leads, did not change in fronto-central, and diminished in the other leads; its slopes were descendent in Pre and ascendant in RPh in both hemispheres. AAP of ß increased in the four leads; in Pre, ß slopes were descendent in parieto-occipital leads of both hemispheres. During RPh, δ slopes were ascendant in right parieto-central and in both parieto-occipital leads. CONCLUSION: The progressive diminution of alpha's desynchronization, which ends in synchronization, is probably due to hyperpolarization of neuronal membranes and represents habituation. This is complemented with synchronization of the delta rhythm in anterior cortical areas and of theta and beta in areas of the right hemisphere.

[Absolute power of cortical oscillations and their topographical distribution in a sample of young adults during resting wakefulness and unspecific attention]. / Potencia absoluta de oscilaciones corticales y su distribución topográfica en una muestra de adultos jóvenes en vigilia inactiva y en atención inespecífica.

INTRODUCTION: The EEG records neuronal membrane potential oscillations that depend on the morpho-functional characteristics of the membrane and of modifications by postsynaptic excitatory (PSEP) and inhibitory (PSIP) potentials. The quantitative EEG (qEEG) measures the absolute power (AP) of oscillations separated in frequencies, resulting from the interaction among subcortical-cortical-subcortical ensembles. The hypothesis is that neuronal networks function at a given frequency and that their APs are codes that, by becoming synchronized in diverse ensembles, generate behavior. OBJECTIVE: To establish the spectral power of cortical oscillations under diverse study paradigms and in different populations. In particular, to identify the AP and topographical distribution of four cerebral frequency bands under resting wakefulness and activation, and to integrate results into a database to establish comparison standards. MATERIAL AND METHODS: Undergraduate students, average age of 20.6 +/- 2.6 years, who participated voluntarily in the study. Recordings were made with a Nicolet EEG. We chose, in the first stage, closed eyes (CE) three samples of 12 s each. In the second stage, we chose pairs of 6 s samples, first with CE and then with OE. For their analysis, we applied the Welch periodogram and we plotted the average AP (AAP) and standard deviation (SD) of delta, theta, alpha, and beta per lead. Differences were compared through non-parametric tests (Wilcoxon and Dunnett T3); setting statistical significance at a = 0.05. RESULTS: Average APs of each frequency band differ significantly in intensity and topographic distribution generating a profile of each rhythm. When opening the eyes, rhythms desynchronized significantly at different intensities in the diverse leads, except for beta in the left fronto-frontal lead. DISCUSSION: Results indicate the existence of cortical ensembles that synchronize at a determined frequency and are modified by visual stimulation, indicating the effects of the subcortico-cortical circuits. The integrated database provides comparison standards to support diagnoses and treatments.

[Desynchronization/synchronization of lateral EEG rhythms during habituation to photostimulation in adults]. / [Desincronización/sincronización de ritmos EEG laterales en la habituación a la fotoestimulación en adultos].

BACKGROUND: Berger related the EEG with cognition; we are attempting to identify which rhythms and circuits participate in habituation, a learning that decreases responses to meaningless stimuli which, changed the absolute power (AP) of EEG oscillations. OBJECTIVE: To characterize habituation, analyzing the AP of four rhythms in lateral regions of both hemispheres (BH), proposing that their diminution, desynchronization (D), means activation whereas their increase, synchronization (S), means inhibition. MATERIAL AND METHODS: qEEG analysis in 83 college students, in waking state with closed eyes, and photostimulated (RPh). The used UAMI/Yáñez software identifies RPh signals and takes 2-s samples before (Pre) and during RPh; the Welch periodogram integrates the AP of the four rhythms. We calculated the average AP (AAP) in Pre and RPh per frequency in bipolar lateral leads per hemisphere. AAP differences were evaluated with the Wilcoxon tests correcting with Bonferroni for repeated samples. Applying the linear regression model, we plotted the AAP distribution slopes during Pre and RPh. RESULTS: We established the differences of the AP of the four rhythms within each hemisphere and between both hemispheres (BH). During PRE, AAP of δ and θ increased whereas α and ß decreased. RPh increased the AAP (p = 0.01) of the four rhythms in fronto-frontal (FF) leads; the increase in δ persisted in fronto-temporal (FT) and temporo-occipital (TO), whereas ß's increase persisted in all leads. The AAP of α decreased with the first RPh (D) increasing with the following ones; its slope starts with desynchronization and ends with synchronization. Theta followed a D/S pattern in temporal leads. Beta followed and ascending (S) slope in all leads. CONCLUSIONS: Habituation results from the D/S of a in all cortical regions, of θ in temporal, of δ in frontal regions and ß in all regions. Synchronization reflects hyperpolarization of neuronal membranes, decreasing their activity.

Assisted diagnosis of attention-deficit hyperactivity disorder through EEG bandpower clustering with self-organizing maps.

The electroencephalogram is an attractive clinical tool given its non-invasive nature, its ability to reflect real-time changes in local cortical activity, and the load of objective bioelectrical measurements that can be derived from it. For decades, the electroencephalogram has been successfully used for diagnosing epilepsy and schizophrenia, among other brain disorders. This paper focuses in the design and implementation of a computer-aided diagnostic tool for establishing the likelihood of presence of Attention-Deficit Hyperactivity Disorder in children, out of routine electroencephalographic recordings obtained during a specific visual stimulation protocol. Classical bandpower features from multiple differential recordings are computed and used as features in a classifier built from a cooperative ensemble of labeled self-organizing maps. Classification accuracy of the proposed system is 0,7 ± 0,11, as estimated from unseen data, a result that points to the idea that such a quantitative diagnostic aid could adequately support the diagnostic task of a clinical expert.

Cambios del EEG por habituación y condicionamiento en niños de tres a 15 años que acuden al Instituto Nacional de Rehabilitación (INR) / EEG changes induced by habituation and conditioning in 3- to 15-year-old children attending the Instituto Nacional de Rehabilitación

During waking, stimuli activate the sensory pathways giving rise to sensation and the response to such stimulation. The electrobiochemical changes and modifications in EEG rhythms event-related synchronization or event-related desynchronization, ERD or ERS) propagated in the specific and unspecific cortex are added to the changes elicited by the responses and to the new signals originated by those same responses, bringing about perception. Diverse factors can alter these glialneuronal circuits, producing alterations in attention processes (ADD) and in the integration with their meaning. The inability to identify signals and integrate correct coordinated responses leads to deficiencies in responding to the environment and to associated morbidities that are added to ADD. ADD and its associated morbidities cause high social and economic impacts and, even more so, because of their persistence into adolescence and adulthood. Therefore, highly accurate diagnostic procedures are needed for these diseases. According to the CIE-10, in the clinical setting symptoms are analyzed without studying the neuro-developmental and neuro-degenerative signs that identify alterations in neuronal circuits. As is known, behavior (including motivation, memory, thoughts) results from the Central Nervous System (CNS) activity, and the EEG records the electrical activity of neurons and synapses of the cerebral cortex, where cognitive processes are most likely to take place. To establish more accurate diagnostic procedures for ADD, we are integrating an electronic database, considering the intensity and cerebral distribution of theta (θ), alpha (α), and beta (β) rhythms. We propose that the ERD of α and β reflects a cortical activation that gives rise to sensory-motor coordination processes. The first stimulations induce ERD, and their repetitions produce its decrement (ERS): ERD habituation. In addition, this ERD to ERS change might be reversed when giving meaning to the stimulation. We present herein the changes in θ, α, and β rhythms induced by repeated photostimulation (RPS), with the same characteristics, that, when presented, requires the subject to press a knob. Hundred-twenty-four children were studied at the Instituto Nacional de Rehabilitación (INR, for its initials in Spanish) in Mexico City. Children were of either gender and aged from 3 to 15 years, separated in four groups of 3-year intervals. During clinical exploration, we searched for possible delays in physical-emotional-intellectual development, epilepsy, and medical or psychological treatments during the last six months, which were considered exclusion factors. Parents were briefed on the study, explaining them that the procedure had a low-risk nature and allowed for the analyzis of the electrical activity of the brain. Once having understood and accepted the procedure, they signed the informed consent form prepared by the institution. Children were explained <> work and that the procedure caused no pain at all. They were asked to close their eyelids during the recordings, and to remain as motionless as possible. The exclusion factors left a sample of 94 children for the habituation analysis and of 47 for the simple conditioning procedures. The EEG was recorded in dorsal decubitus position, with a digital 24-channel electroencephalograph, according to the 10/20 international system. In addition, we recorded eye movements and the EKG. After 5-min recordings with closed eyelids, photo-stimulation was started at 5 flashes per second during 2s, repeated 20 times (RPS), at 21 to 25 sec. intervals. After finishing the series, 5 min rest were provided, and then a round device with a knob was placed in the children's hands, telling them to press the knob at the start of the RPS and to release it at the end. Analyses were performed with 1.6 to 40 Hz bandwidth filters. From the bipolar leads, samples recorded 2 sec. before, during, and after the 1st, 5th, 10th, 20th associations (PS-knob pressing) were manually chosen. For conditioning analyses, we also measured the response latency. The Fourier's FT was applied to the samples and the absolute potency (AP) was calculated for θ (4.0 to 7.5 Hz), α (8.0 to 12.5 Hz), and β (13 to 20 Hz). The average of these frequencies was obtained for each hemisphere (Right, RH; Left, LH) and for both (BH). Wilcoxon's test for related samples was used with (α > 0.05 as significant. Analyses of the AP of the three frequencies in all children revealed a background activity below 10 µV². The first RPS produced a decrease in the AP of θ and α, with an increase in β in BH. At the 5th RPS, θ and α continued to decrease along with an increase in β. At the 10th RPS, θ and α decreased less but the increase in β persisted. At the 15th RPS, θ continued to decrease but α increased in the LH and decreased somewhat in the RH, whereas β continued its increase in BH. At the 20th RPS, the AP of θ and a decreased in BH, but the difference was smaller than that recorded during the previous RPS. The AP of β continued to increase in BH. The most relevant aspects are: a) in G-1 (children aged 3 to 6 years), the AP of the three frequencies is higher, predominating θ, which is twice the magnitude of that of the whole group; b) the 1st PS produced an increase in the AP of all three frequencies, which was not recorded in the other groups (children aged 6.5 to 15 years); c) in G-4 (children 12.5 to 15 years of age), the 1st and 5th PS produced a clear diminution in the AP of θ and a (ERD), which was smaller at the 10th RPS and reversed at the 15th and 20th RPS (ERS). After indicating to the children that with each RPS they would have to press a knob, the background activity increased to 12 µV². During the 1st association (assoc), the AP of θ and α decreased with a slight decrease in β; the response latency was 930 ms. At the 5th assoc, θ decreased together with a small increase in a and β, and the response latency decreased to 750 ms. On the 10th and 15th assoc, the three frequencies increased and the latency decreased to 650 and 640 ms, respectively. On the 20th assoc, the AP increase of each rhythm was smaller, and the latency increased to 750 ms. The EEG analysis per group revealed a higher AP for 0 in the smaller children that decreased along increasing age together with a relative increase in a, which reached its maximal value in G-4. In the four groups, the RPS induced an undulating tendency towards a decrease in the EEG desynchronization that represents habituation, being more noticeable in G-4. Although the reached synchronization level did not reflect a better inhibition, as described in adults, it suggested that, in these children, the inhibitory activity on sensory control has not yet developed completely. Another important finding is that in G-1, the 1st RPS induced and increase in θ and α that was not observed in the other groups.

Algunos cambios del ambiente activan las vías sensoriales generando la sensación y la respuesta a dicha estimulación. Los cambios electrobioquímicos modifican el EEG que al propagarse en la corteza cerebral se suman a los potenciales que generan las respuestas y éstas producen nuevas señales que dan lugar a la percepción. Diversos factores pueden alterar la organización de esos circuitos glioneuronales produciendo trastornos de la atención (TDA), de su integración con su significado, lo que regula el tipo e intensidad de respuestas adecuadas al contexto social. La discapacidad de estas funciones genera comorbilidades que se suman al TDA. Estas enfermedades son de alto impacto socio-económico y cultural y lo son más cuando persisten en la adolescencia y la adultez. Por esto es necesario desarrollar metodologías diagnósticas de alta precisión. Actualmente se acepta que la conducta integral resulta de la actividad del Sistema Nervioso (SN). El EEG registra la actividad eléctrica de las neuronas de la corteza cerebral donde se realizan procesos cognitivos. Para caracterizar el EEG estamos integrando, en una base de datos electrónica, la intensidad y distribución cerebral de los ritmos delta (Δ), theta (θ), alfa (α) y beta (β). Proponemos que la desincronización (DRE) refleja la activación cortical, base de los procesos de coordinación sensoriomotora. Las primeras estimulaciones producen DRE que, al repetirse, disminuyen la habituación de la DRE. Además, es posible que se invierta este cambio DRE a sincronización (SRE) al darle significado a la misma estimulación. En este trabajo se presentan los cambios de θ, α y β ante la fotoestimulación repetida y cuando el sujeto tiene que presionar un botón al inicio de dicha estimulación. Sujetos y método Se atendieron 124 niños, de tres a 15 años, separados en cuatro grupos con intervalos de tres años. En el interrogatorio clínico se indagó el posible retraso del desarrollo físico-emocional-intelectual, de epilepsia o tratamientos médicos o psicológicos convirtiéndose en factores de exclusión. A los niños, delante de los padres, se les explicó cómo funciona su cerebro, que el estudio no produce dolor, que estarán acostados con los párpados cerrados (OC), permaneciendo lo más inmóviles posible, los padres al comprenderlo y aceptar firmaron la autorización. Los factores de exclusión dejaron 94 niños para análisis de habituación y 47 para condicionamiento. El EEG se registró utilizando los montajes bipolares A-P parasagitales del sistema internacional 10/20, además se registraron los movimientos oculares y el EKG. El sujeto con OC se fotoestimulaba 20 veces (FR a 5/s X 2s). Después de 5 min de terminada la serie se les ponía en la mano dominante un aditamento con un botón, indicándoles que lo apretaran al inicio de cada FR y lo liberaran al terminarse (asociaciones). El análisis se efectuó con filtro de 1.6 y 40 Hz. Seleccionando manualmente, de la 1era, 5ª, 10ª 15ª y 20ª FR muestras de registros bipolares de 2s antes, durante y después. Para el condicionamiento se agregó la medición de la latencia de la respuesta. Se aplicó la TRF y se calculó la Potencia Absoluta (PA) de θ (4.0-7.5 Hz), α (8.0-1 2.5 Hz) y β (1 3-20 Hz), se obtuvo el promedio en cada hemisferio (HI, HD) y de ambos (AH). Se utilizó la prueba de Wilcoxon con α >0.05. Resultados El promedio de la PA de la actividad de fondo, de todos los niños, está por debajo de 10 µV². La 1era FR disminuye la PA de θ y de α con incremento de β en AH. En la 5ª FR disminuye θ y α con incremento de β. En la 10° disminuye menos θ y α, persistiendo el incremento de β. En la 15ª continúa la disminución de θ, pero aumenta α en el HI y disminuye en el HD. En AH se incrementa β. En la 20° se vuelve a disminuir θ y α en AH; sin embargo, el rango de la diferencia es menor que el registrado en anteriores FR. La PA de β sigue aumentando en AH. El análisis por grupo muestra que en el G-1, la PA de los tres ritmos es mayor, con predominio de θ, siendo del doble del grupo total. En la 1era FR incrementa la PA de los 3 ritmos, lo cual no se registró en los otros grupos. En el G-4, la 1era y 5ª FR disminuyen la PA de θ y de α (DRE), siendo menor la disminución en la 10ª y se invierte en la 1 5ª y 20ª (SER). Consecutivamente a la explicación de que con la FR deben presionar el botón, se incrementa el promedio de la PA a 12 µV² en promedio de la muestra. En la 1era Aso disminuye la PA de 6 y de θ incluyendo una discreta disminución de β, la latencia es de 930 ms. En la 5ª Aso disminuye θ con pequeño incremento de θ y α y la latencia es de 750 ms. En la 10ª y 15ª continúa el incremento de los tres ritmos y la latencia disminuye a 650 y 640 ms, respectivamente. Mientras que en la 20ª el incremento de la PA de cada ritmo es menor y la latencia se incrementa a 750 ms.

Eficiencia de celdas generadoras de gases oxidantes alimentadas con energía eléctrica o solar / Efficiency of oxidant gas generator cells powered by electricity or solar energy

Las enfermedades causadas por microorganismos contaminantes del agua siguen siendo un grave problema en países como México. La cloración mediante gas cloro o compuesto de cloro es uno de los mejores métodos para tratar el agua destinada al consumo humano. Sin embargo, la dificultad en el manejo del gas cloro y la ineficiencia de los sistemas de dosificación de soluciones de hipoclorito, debida a factores sociopolíticos, económicos y culturales, a veces han restado utilidad a estos procedimientos de cloración, sobre todo en comunidades rurales alejadas y de difícil acceso. Por todo ello se han desarrollado tecnologías apropiadas para la desinfección del agua mediante la generación in situ de gases oxidantes (cloro y ozono) a partir de la electrólisis de una solución de sal común, el llamado sistema MOGGOD. La evaluación simulada del sistema mediante un modelo hidr—lico permitió calcular sus costos parciales y totales. Con alimentación del sistema mediante energía eléctrica de la red se obtuvo una eficiencia de 90 por ciento y se generaron en 10 horas gases suficientes para desinfectar cerca de 200 m3 de agua a un costo aproximado de N$ 8 (US$1,30). La celda electrolítica funciona también con energía eléctrica suministrada mediante célula fotoeléctrica, en cuyo caso los costos de inversión son mayores. El sistema alimentado con células fotovoltaicas puede estar justificado en comunidades aisladas que carecen de energía eléctrica pero que cuentan con un sistema de distribución de agua por gravedad

Eficiencia de celdas generadoras de gases oxidantes alimentadas con energía eléctrica o solar / Efficiency of oxidant gas generator cells powered by electricity or solar energy

Las enfermedades causadas por microorganismos contaminantes del agua siguen siendo un grave problema en países como México. La cloración mediante gas cloro o compuesto de cloro es uno de los mejores métodos para tratar el agua destinada al consumo humano. Sin embargo, la dificultad en el manejo del gas cloro y la ineficiencia de los sistemas de dosificación de soluciones de hipoclorito, debida a factores sociopolíticos, económicos y culturales, a veces han restado utilidad a estos procedimientos de cloración, sobre todo en comunidades rurales alejadas y de difícil acceso. Por todo ello se han desarrollado tecnologías apropiadas para la desinfección del agua mediante la generación in situ de gases oxidantes (cloro y ozono) a partir de la electrólisis de una solución de sal común, el llamado sistema MOGGOD. La evaluación simulada del sistema mediante un modelo hidráulico permitió calcular sus costos parciales y totales. Con alimentación del sistema mediante energía eléctrica de la red se obtuvo una eficiencia de 90 por ciento y se generaron en 10 horas gases suficientes para desinfectar cerca de 200 m3 de agua a un costo aproximado de N$ 8 (US$1,30). La celda electrolítica funciona también con energía eléctrica suministrada mediante célula fotoeléctrica, en cuyo caso los costos de inversión son mayores. El sistema alimentado con células fotovoltaicas puede estar justificado en comunidades aisladas que carecen de energía eléctrica pero que cuentan con un sistema de distribución de agua por gravedad

Diseases caused by microbial contaminants in drinking water continue to be a serious problem in countries like Mexico. Chlorination, using chlorine gas or chlorine compounds, is one of the best ways to treat drinking water. However, difficulties in handling chlorine gas and the inefficiency of hypochlorite solution dosing systems--due to sociopolitical, economic, and cultural factors--have reduced the utility of these chlorination procedures, especially in far-flung and inaccessible rural communities. These problems led to the development of appropriate technologies for the disinfection of water by means of the on-site generation of mixed oxidant gases (chlorine and ozone). This system, called MOGGOD, operates through the electrolysis of a common salt solution. Simulated system evaluation using a hydraulic model allowed partial and total costs to be calculated. When powered by electrical energy from the community power grid, the system had an efficiency of 90%, and in 10 hours it was able to generate enough gases to disinfect about 200 m³ of water at a cost of approximately N$ 8 (US$ 1.30). When the electrolytic cell was run on energy supplied through a photoelectric cell, the investment costs were higher. A system fed by photovoltaic cells could be justified in isolated communities that lack electricity but have a gravity-fed water distribution system.

Pruebas de esfuerzo en banda sin-fin en jóvenes a 2800 m SNM / Treadmill test in young steers at 2800 m above sea level

La SSA fomenta entre otras actividades: a) el establecimiento de estándares de variables biológicas para comparación entre diferentes individuos: b) la detección temprana de alteraciones fisiopatológicas y c) el desarrollo de tecnologías apropiadas como base de la atención médica primaria. Como parte de estos programas se estudió, con equipo SSA-CEDAT, una muestra aleatoria de estudiantes del Colegio de Bachilleres, plantel Cuajimalpa, situado a 2800 m SNM. Se analizó el peso y talla corporal, frecuencia cardiaca (FC), presión sanguínea sistólica (PSS) y diastólica (PSD) en reposo, sentados, parados y realizando ejercicio físico en una banda sin-fin. Se describe una población con características corporales similares a las descritas para otras poblaciones. En reposo presentaron valores de FC homogéneamente distribuidos, excepto tres personas con niveles mayores a dos desviaciones estándar (DE). Las mujeres al levantarse, incrementaron FC en promedio 27 Latidos por minuto (Lpm) y los hombres 22. Durante el ejercicio, la curva de FC es más homogénea con pendiente ascendente discreta bajo coeficiente de correlación que sugiere baja capacidad física de la población estudiada. En las siguientes etapas, varios valores de FC quedan dos DE por debajo del promedio. Se detectaron cinco mujeres y tres hombres cuyos valores de PSS en reposo están más allá de dos DE del promedio de la muestra estudiada. Durante el ejercicio presentaron aumentos superiores a 28 mmHg en PSS, sin cambio importante en PSD. No obstante su baja respuesta cardiaca, los tiempos de caminata en la banda sin-fin quedan dentro del nivel calificado de buenos y excelentes en las tablas del Instituto Nacional de Cardiología. Se discuten nuevos procedimientos para el análisis de la FC instantánea y del reflejo presorreceptor y su significado funcional. En conclusión se describe un procedimiento aplicable en la atención primaria de la salud, con medición del reflejo presorreceptor que permite predecir el desarrollo de hipertención sanguínea y por lo tanto evitar los altos costos de esa enfermedad silenciosa

Técnica CEDAT para el diagnóstico presuntivo de fibrosis quística / CEDAT atechnique for the presumptive diagnosis of cystic fibrosis

Se desarrolló una técnica para producir tiras reactivas para la determinación cualitativa de cloruos en el sudor como una prueba selectiva de diagnóstico de firbosis quística. Se realizaron dos pruebas comparativas en 23 niños, en una se les aplicó en la piel papel reactivo (CEDAT) para la determinación coalitativa de la concentración de cloruros en el sudor y, en la otra, se determinaron con aparatos especializados y de alto costo los milimoles de Cl por litros de sudro (mmol/l). Los papeles reactivos se decloraron completamente en tres,y siete presentaron dedecloraciónen la orillas y puntos en toda ls tira reactiva, algunos de los pintos eran amarrillentos. En estos casos la determinación instrumental reflejó una consentración de cloruros entre 90 y 130 mmol/L. En otras siete pruebas la decoloración de la tira reactiva fue ligera, en cuatro de éstas los papeles reactivos sólo tuvieron algunos puntos amarrillentos y en tres no cambiaron; la concentración en estos casos estuvo entre 12 y 52 mmol/L. Se eliminaron 6 casos estuvo entre 12 y 52 mmol/l. Se eliminaron 6 caos debido a que en 3 no se pudo efectuar la determinación instrumental de cloruros y en las otras tres no hubo suficiente sudor para utilizar los dos procedimientos. La Asociación Mexicana de Fibrosis Quística considera resuelto positivo un valor igual o superior a 90 mmol/l de cloruros, que es cuando el papel reactivo se decolora completamente en las orillas o con puntos blancos y amarrillos en toda su extensión. Por lo tanto, esta técnica permite hacer una selección rápida y económica de los niños que pudieran tener fibrosis quística.